1. Field of the Invention
This invention relates to a process for producing a molded product. More particularly, it relates to a process for producing a molded product of a good appearance having a good moldability, a good luster and a superior uniformity of a product appearance.
2. Description of the Related Art
The appearance of conventional hollow vessels and multi-layer sheets has been still insufficient to satisfy the needs of markets. Thus, improvement in the surface appearance, particularly, notable improvement in the luster and the uniformity of the surface have become a very serious problem. Polypropylene resins have a number of superior characteristics such as stiffness, impact strength, heat resistance, hygienic properties, resistance to steam permeability, moldability, etc.; hence the resins have been very often used for producing hollow vessels according to a blow molding, and multi-layer sheets according to a multi-layer molding. On the other hand, however, the resins have drawbacks of being inferior in the gas barrier properties against oxygen, nitrogen, CO.sub.2 gas, etc. Thus, for the use applications of food vessels for soft drinks, flavoring materials, edible oils, etc., hollow vessels and multi-layer sheets wherein polyolefin resins are used as the inner and outer layers and resins having good gas-barrier properties such as ethylene-polyvinyl alcohol copolymer, nylon, etc. are used as the intermediate layer, have been used in a large quantity.
As a countermeasure for solving such a problem, for example, there has been known a process of using random ethylene-propylene copolymer as the outermost surface layer of a multi-layer vessel to improve the surface luster, as disclosed in Japanese patent application laid-open No. Hei 2-215529, but in the case of hollow molding, since degassing of air in the mold is insufficient; hence the luster is insufficient and luster unevenness occurs. Thus, a problem has been raised that the commodity value cannot be sufficient and the use applications are limited.